The disclosure relates to a device for measuring resistivity adapted to be mounted on a downhole tool intended to be lowered in a wellbore.
For measuring resistivity in a wellbore, a downhole tool may comprise electrodes that generate currents into the formation surrounding the borehole and measure a current generated in the formation and a data processing module for processing, storing or transferring the measurement to the surface for instance. To ensure an accurate measurement, the electrodes are positioned so that they are on the external surface of the body of the tool and in contact with the drilling fluid present in the borehole. The data processing module is positioned in an atmospheric chamber situated inside of the tool in order to avoid exposing this module to the harsh conditions existing inside of the wellbore. The electrical signals measured by the electrodes are transferred from the electrodes to the data processing module via a coaxial cable connected to the electrodes which may generate perturbations in the signals.